Let's just say that if Morrowind's MQ had you unite the Ashlanders and Great Houses by sitting at a table for 5 minutes, I would be just as disappointed. Skyrim's MQ is feels rushed to it's conclusion, like it's missing 1/3 of what should be there.
Yeah. I played Morrowind for years... and only got to completing the main quest in the last few months. I wasn't crazy about it at all and really just grinded to finish it because I was giving my old Xbox away to my cousin. It was one of those, "well, I've played that game for years and never finished the mainquest. May as well do it now before I lose the opportunity". Yeah, it was anti-climactic. At least with Skyrim's you get some cool things for completing it... but, like Morrowind, it doesn't really hold my interest as far as story telling goes. There are a few really cool moments, but there were in Morrowind as well. Oblivion started out promising for me, but when I realized that everything was a fetch quest or a "close this Oblivion gate... now this one... now this one..." it wore thin. And I was really disappointed with the sorry excuse for an epic battle at Bruma. I think that bothered me most. The most each town could spare was two guards a piece. Lame.
But none of that broke any of the three games for me. The main quests are what they are. Bottom line is that everything else about each of those games is fabulous. I have devoted a huge chunk of my life to playing TES games because of the *freedom* they provide, main quests aside.